Amulet of Nyx

While wearing this item, you can Wild shape into any beast or monstrosity, at double your max CR. You can stay in the beast or montrosity shape for a number of hours equal to your druid level.

Nyx's Curse. While your are in a beast or monstrosity shape, the amulet remains around your neck. If the amulet is taken or lost while you are in this shape, you are cursed to remain in that shape until you die or regain the amulet.

A druid name Creot Kethril used this amulet to enchace his Wild Shape abilities. However, the amulet was stolen while he was transformed into an owlbear. He remained an owlbear for over 20 years until the amulet was returned and his curse was lifted.